Files with chm extension are mainly related to Microsoft compiled HTML help file format. CHM is acronym for Compiled Help Modules.

There are 4 other file types using
the CHM file extension!

empty icon.chm - Chameleon source font

empty icon.chm - ChemDraw chemical structure

empty icon.chm - Two Worlds 2 animation file

empty icon.chm - SWAT soil chemical input data

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CHM file extension - Microsoft compiled HTML help module

What is chm file? How to open chm files?

File extension chm is used for Microsoft compiled HTML help files. CHM  is acronym for Compiled Help Modules. This format is used in Microsoft HTML Help, the standard help system for the Windows platform.

A .chm file represents a collection of HTML documents and other data such as images and JavaScript compressed into a single file.

These chm files contain a number of powerful features present in the specifications available here including: Table of Contents, Index of keywords and Full-text search functionality.

In the past ebooks were often saved in CHM format and some readers even existed, but it's not longer used for that purpose any formats like MOBI or EPUB are used instead

Updated: March 13, 2023

The default software associated to open chm file:

Microsoft Windows Help icon

Microsoft Corporation logoMicrosoft Windows Help  Microsoft Windows software

Company or developer:
Microsoft Corporation

Microsoft Windows Help is used to create help files for Microsoft Windows operating system and other Microsoft applications. Windows Help SDKs are different for every version of Windows it can be called Windows Help, Help and Support Center, Assistance Platform 1.0 Client - Windows Vista Help SDK, Microsoft Windows: HTML Help 1.4 etc.

Microsoft HTML Help Workshop icon

Microsoft Corporation logoMicrosoft HTML Help Workshop  Microsoft Windows software

Company or developer:
Microsoft Corporation

Microsoft HTML Help Workshop is help documents authoring application.

Microsoft Windows icon

Microsoft Corporation logoMicrosoft Windows  Microsoft Windows software

Company or developer:
Microsoft Corporation

A family of operating systems developed by the Microsoft Corp. The first Windows was released in 1985 as a GUI add-on to MS-DOS. MS-DOS based Windows versions were developed to 2000, when was released the last version called Windows ME. Windows based on NT core started in 1993. Windows NT family are developed to these days, the latest version is called Microsoft Windows 11.

Help how to open:

Various readers for CHM format exist, some are available direclty in Windows by default.

How to convert:

Some tools are able to export data from *.chm files.

Find conversions from chm file:

chm to fb2

chm to hnd

chm to pdf

Find converter to chm file type:

docx to chm

hnd to chm

File identification strings:

HEX code: 49 54 53 46

List of software applications associated to the .chm file extension

Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open chm file, edit chm file, convert chm file, view chm file, play chm file etc. (if exist software for corresponding action in's database).

Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting chm files.

Software that open chm file - Microsoft compiled HTML help module

Programs supporting the exension chm on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about listed programs for open chm file action.

Microsoft Windows:


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